Porous Glasses

Sol‐Gel and Porous Glass‐Based Silica Monoliths with Hierarchical Pore Structure for Solid‐Liquid Catalysis

“…As a result, an interconnected structure of a silica-rich phase and an unstable alkali-rich borate phase is created from the beginning. Finally, the latter is selectively leached with an acid or by a combined acid/alkaline treatment at temperatures between 25 and 90°C [82]. Porous glasses prepared in this way are characterized by pore sizes from < 2 nm up to 1 mm and flexible pore volumes of 0.3 -2 cm 3 g -1 .…”

“…The macroscopic dimensions of the monoliths, their macropore size, skeleton thickness, and macroporosity can be tuned by the number of tubes in the starting bundle, the tube diameter, wall thickness, and the drawing velocity and pressure regime in the hot zone of the furnace [89,90]. Porous glasses are characterized by the typical surface chemistry of amorphous silica materials [82]. This allows the direct application of well-established procedures for surface activation and modification, or immobilization of functional species (enzymes, dyes, catalysts).…”

Crystallization Behavior of Acetaminophen in Nanopores

“…Controlled porous glasses (CPGs) with pore diameters of 10, 22, 43, 60 and 103 nm are obtained by leaching of phaseseparated sodium borosilicate glasses containing 70 wt.-% SiO 2 , 23 wt.-% B 2 O 3 and 7 wt.-% Na 2 O [21,22]. Nanoporous glass monoliths have been prepared in three steps: (i) generation of the desired shape by various techniques of sawing, (ii) heat treatment for phase separation in the temperature range between 530 and 720°C, (iii) removal of the soluble phase by acid or combined acid/alkaline leaching treatment.…”

Recent advances in the synthesis of hierarchically porous silica materials on the basis of porous glasses

“…The resulting textural and mechanical product properties strongly depend on the composition of the initial glass, the temperature and the duration of the heat treatment for phase separation and the leaching (acidic extraction to remove the sodium borate phase followed by alkaline treatment to remove siliceous residues if desired) conditions. 2 Typically, porous glasses prepared from phase separated alkali borosilicate glasses exhibit a monomodal pore size distribution. Recent studies in the field of porous glasses continue to focus on the controlled manipulation of their functional as well as textural properties.…”

“…for enzyme immobilisation, 3,4 as transparent supports for photochemical applications, 5,6 as reference materials for texture analytical methods like mercury intrusion, PALS or nitrogen physisorption 7 and also as a model material with well defined porosity for diffusion studies in porous media. 8 The most common route for preparing porous glasses is the leaching of phase separated alkali borosilicate glasses, 2 as schematically shown in Fig. 2.…”